An ignition coil control device includes: an energization control unit that controls to energize an ignition coil by first energization control and second energization control shorter in energization time than the first energization control; a cruise area determination unit that determines that a driving area of a vehicle is located in a cruise area on the basis of a throttle opening and an engine speed; and an integration counter that is incremented every predetermined time when the first energization control is being executed in the cruise area and is decremented every predetermined time in other cases. When a counter value of the integration counter reaches an upper limit value, a cooling process of switching from the first energization control to the second energization control is executed. Such ignition coil control device can appropriately switch energization time while preventing excessive heating of an ignition coil without using a current sensor.

An ignition control device is provided with an ignition coil including a primary coil and a secondary coil, a main ignition circuit performing a main ignition operation, an energy input circuit that performs an energy input operation for superposing a current having the same polarity to a secondary current, in which a signal generation circuit is provided to generate, based on a main ignition signal that controls the main ignition operation, at least one of an energy input signal controlling the energy input operation and a target secondary current command signal commanding a target secondary current value.

An ignition coil control device includes: an energization control unit that controls to energize an ignition coil by first energization control and second energization control shorter in energization time than the first energization control; a cruise area determination unit that determines that a driving area of a vehicle is located in a cruise area on the basis of a throttle opening and an engine speed; and an integration counter that is incremented every predetermined time when the first energization control is being executed in the cruise area and is decremented every predetermined time in other cases. When a counter value of the integration counter reaches an upper limit value, a cooling process of switching from the first energization control to the second energization control is executed. Such ignition coil control device can appropriately switch energization time while preventing excessive heating of an ignition coil without using a current sensor.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.

In an implementation, a method of operating an ignition circuit can include enabling a charge path control circuit and a switch circuit to charge a primary winding of an ignition coil of the ignition circuit until a threshold current is reached in the primary winding. After reaching the threshold current in the primary winding, the method can include maintaining a current in the primary winding of the ignition coil in correspondence with a current limit by alternatively activating and deactivating the charge path control circuit complementary to alternative activation and deactivation of a circulating-current path control circuit. During the maintaining the current in the primary winding, the method can include initiating a spark in a spark plug included in the ignition circuit, the initiating the spark including controlling an amount of energy delivered from the primary winding to a secondary winding of the ignition coil.

An ignition control device is provided with an ignition coil including a primary coil and a secondary coil, a main ignition circuit performing a main ignition operation, an energy input circuit that performs an energy input operation for superposing a current having the same polarity to a secondary current, in which a signal generation circuit is provided to generate, based on a main ignition signal that controls the main ignition operation, at least one of an energy input signal controlling the energy input operation and a target secondary current command signal commanding a target secondary current value.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.

In an internal combustion engine which performs a homogeneous lean combustion mode and a stratified lean combustion mode, there is provided a new internal combustion engine control device capable of obtaining a stable combustion state by decreasing influences of delay of an air flow and a degree of change of a transient state and smoothly performing switching between the homogeneous lean combustion mode and the stratified lean combustion mode. Accordingly, in the present invention, when switching between the stratified lean mode in which a compression stroke injection is performed by a direct injection injector 7 and the homogeneous lean combustion mode in which an intake stroke injection is performed by the direct injection injector 7 is performed, a predetermined delay time t is provided from at least a switching operation of a tumble control valve 6, a switching operation between the compression stroke injection and the intake stroke injection is performed, and the delay time t is set so as to correspond to a magnitude of the degree of change L of the transient state. A switching timing between the compression stroke injection and the intake stroke injection is controlled according to the flow delay of an air control system such as the tumble control valve 6 and the degree of change L of the transient state, and thus, it is possible to improve combustion stability in a combustion chamber.

A method for determining a need for changing a spark plug of a combustion engine, comprising the following steps: monitoring a current flowing through the spark plug, analyzing the current and thereby determine a time interval that is indicative for the time between application of a voltage to the spark plug and formation of an arc discharge between electrodes of the spark plug, creating a signal indicative of the need to change the spark plug if the duration of the determined time interval is outside predefined bounds.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.